6ES7 231-5PD32-0XB0 V2.1 Firmware Update for TIA Portal V20

1. Problem Overview

When an S7-1200 CPU is configured with a SM 1231 RTD analog input module ordered under MLFB 6ES7 231-5PD32-0XB0 in TIA Portal V20, the engineering tool requires the signal module (SM) to be loaded with firmware V2.1 (or higher, currently V2.1.1). Modules that are still at V2.0 or V2.0.3 trigger a configuration-mismatch diagnostic and prevent the project from going online cleanly. The user-visible symptom is the device view marking the SM with a yellow warning, the message "Firmware version of the plugged module is not the same as the firmware version of the configured module," and a corresponding entry in the diagnostics buffer of the S7-1200 CPU (event ID 0xE400 / 0xE401 family, depending on CPU firmware).

This article documents the exact root cause observed on TIA Portal V20 builds, the official Siemens-supported recovery paths, and the verification procedure to close the mismatch without re-flashing the CPU or losing the project archive.

2. Affected Hardware Identification

The MLFB 6ES7 231-5PD32-0XB0 decodes as follows:

Module electrical and functional key data (from the SIMATIC S7-1200 Programmable Controller System Manual, edition 2024):

3. Root Cause Analysis

TIA Portal V20 ships with a refreshed device description for the SM 1231 RTD family. The catalog entry for 6ES7 231-5PD32-0XB0 was raised from the previous V2.0 / V2.0.3 baseline to V2.1.1 as the minimum online firmware the configuration will accept. The check is performed at three layers:

1. Offline configuration check – When the project is compiled, the device view flags the SM with a yellow triangle and the tooltip reads "Firmware V2.0 of the configured module differs from the firmware V2.1 of the catalog entry".
2. Online compare check – Going online (Ctrl+K or the "Go online" button) raises a type-incompatibility error on the SM. The SM shows up in the "Incompatible devices" filter.
3. CPU diagnostics buffer – A non-fatal diagnostic event is appended referencing the slot number of the SM and the expected vs. actual firmware. TIA Portal reads this entry into Online > Diagnostics.

The mismatch is not a bug in the module – V2.0.3 was the last release that TIA Portal V17 / V18 considered compatible. With V20, Siemens consolidated catalog metadata and now requires V2.1+ to use the module with the latest configuration blocks (notably, the additional channel-level filter and the expanded wire-break diagnostic bits added in V2.1). Older firmware versions are still bootable but cannot be configured by V20 unless a corresponding older TIA catalog is used.

4. Required Files and Prerequisites

Before starting, gather the following:

• S7-1200 CPU with firmware V4.5 or higher (CPU 1211C/1212C/1214C/1215C/1217C, CPU 1212FC/1214FC/1215FC). Lower CPU firmware does not support the V2.1 SM firmware loader; check via Online > Accessible devices before continuing.
• TIA Portal V20 (any service pack) with the matching HSP (Hardware Support Package) for the SM 1231 RTD. The HSP is delivered via the TIA Administrator in V20 and is also published as a standalone package on the Siemens Industry Online Support portal. Without the HSP, the catalog entry remains at V2.0.x.
• Ethernet or PROFINET path between the engineering PC and the S7-1200 CPU, or the Web server of the CPU reachable over HTTP/HTTPS.
• The official Siemens firmware update package for 6ES7 231-5PD32-0XB0 – V2.1.1. Reference: Firmware update for S7-1200 ANALOG INPUT SM 1231 RTD, 4 AI. The entry is a recommended update that also prevents accidental downgrade.
• For HMI/operator panel users: the corresponding Pro-face TIA Portal Ethernet Driver V1.17.25 (or newer) on GP6000 series or WinGP, if the panel is part of the same commissioning cell.

5. Solution Path A – Firmware Update via the CPU Web Server

This is the most field-friendly method because it does not require a TIA Portal project to be open and can be run from any browser on the engineering network.

1. Open the S7-1200 Web server in a browser at http://<CPU-IP>/. Log in with the Web server user that has Firmware update privilege (default user "admin" if the Web server is on default settings; otherwise a user in the "Web server administrator" role).
2. Navigate to Module Information > Firmware update. The page lists the plugged SM 1231 RTD as SM 1231 RTD 4AI 6ES7 231-5PD32-0XB0 with current firmware V2.0.3.
3. Click Browse and select the previously downloaded firmware file from the Siemens support entry above. The file is typically named SM1231_RTD_4AI_V2_1_1.upd.
4. Confirm the slot (usually slot 1 for the first SM after the CPU) and click Update. The CPU stays in RUN; the SM reboots and the Web server shows the new firmware version (V2.1.1) within 30–60 seconds.
5. Verify by reloading the Web page and checking the firmware version line. Clear the CPU diagnostics buffer (Online > Diagnostics > Clear) to drop the historical mismatch event.

6. Solution Path B – Online Firmware Update from TIA Portal V20

This method is preferred when the project is already open and the SM is already added to the device configuration.

1. In the project tree, right-click the S7-1200 CPU and choose Online > Go online. TIA will report the SM as "incompatible" because of the firmware mismatch; that is expected at this stage.
2. Without going offline, right-click the SM 1231 RTD in the device view and select Online & diagnostics. Switch to the Firmware update tab.
3. If the HSP is installed (see Section 7), the catalog automatically offers the V2.1.1 update image. If only the V2.0.x image is shown, the TIA Portal HSP is missing – close this dialog and install the HSP first.
4. Confirm the update. TIA Portal will load the new firmware into the SM, then run a verification read. The SM drops out and reconnects to PROFINET/PROFIBUS if used; for S7-1200 distributed I/O scenarios, no restart of the CPU is required.
5. After completion, click Go online again. The SM should now show Compatible in the comparison column. Compile the project (Hardware) and download to clear the residual diagnostic.

7. Solution Path C – Install the Hardware Support Package (HSP)

If the V2.1 / V2.1.1 catalog entry is not visible in TIA Portal V20, the HSP is missing. HSPs are managed through the TIA Administrator on TIA Portal V20:

1. Close TIA Portal V20 if it is running.
2. Open TIA Administrator (Start menu > Siemens Automation > TIA Administrator).
3. Select the installed TIA Portal V20 instance and click Install HSP / Support Packages. The administrator launches the HSP Installation tool.
4. Point the tool at the HSP file you downloaded from Siemens Industry Online Support (file extension .hsp, e.g. HSP_V20_SM1231_RTD_2024Q3.hsp). The package is found by searching "SM 1231 RTD" in the Siemens product tree.
5. Confirm the license terms. The HSP installs into the TIA Portal catalog; restart TIA Portal V20 to load the new module description.
6. Reopen the project. Right-click the SM 1231 RTD in the device view and select Change device / variant. Confirm the firmware slot now shows V2.1.1 as the expected value. The yellow triangle should disappear after the next compile.

The full module description for V20 is referenced in Signal modules (SMs) – TIA Portal V20 documentation. The reference confirms the catalog upgrade path and includes the new advanced configuration blocks delivered with the V2.1 firmware.

8. Solution Path D – Run the Project under an Older TIA Portal Version

This is a workaround, not a fix. Use it only if hardware-side update is not possible (locked machine, customer change-control, or test bench).

1. Open the project in TIA Portal V17 or V18. Both versions accept SM 1231 RTD V2.0.3 out of the box.
2. Do not save the project upward to V20 unless the SM is updated first. The cross-version archive will lock in the V2.0 catalog metadata and re-create the mismatch on the next V20 open.
3. Note that the project will lose access to new V20 blocks (e.g., the new OPC UA companion specification helpers) while it remains in the older catalog.

9. Firmware Compatibility Matrix

The jump between V19 and V20 in the catalog column is the source of the user's symptom: a V2.0.3 module is at or above the V19 minimum, but below the V20 minimum.

10. Verification Procedure

Run the following checks in order. Each step confirms the previous one before the project is released.

1. Web server: Reload the CPU Web page /> Module Information. The SM 1231 RTD row should show Firmware V2.1.1 and Status: OK.
2. TIA online compare: In TIA Portal V20, click Go online. In the device view, the comparison column for the SM should show a green check mark on the firmware row. The diagnostics buffer should not contain any new Firmware mismatch events since the last clear.
3. Forcing diagnostics: Disconnect one RTD wire on channel 0. The SM should raise wire-break (channel status bit) within one conversion cycle (≤100 ms at 100 ms integration time). Reconnect. The bit should clear. This proves the V2.1 channel-level diagnostics are active.
4. Conversion timing: Place a Pt100 simulator on channel 0 at 0.00 °C. Read the input word in a watch table. The value should be 0 ±0.1 °C after thermal stabilization of the simulator (allow 30 s).
5. CPU diagnostics buffer: Right-click the CPU in the online view and choose Diagnostics buffer > Clear all. Cycle the SM power (pull and re-seat the module). No firmware-mismatch event should appear.

11. Related Modules and Variant Notes

The catalog refresh in V20 also touches the following SM 1231 variants. The same procedure applies if a similar mismatch is encountered:

• 6ES7 231-5PD30-0XB0 – SM 1231 RTD, 4 AI, older 15-mm variant. Note: this is a 4-wire RTD input only and is end-of-life; replace, do not attempt firmware update.
• 6ES7 231-5PD50-0XB0 – SM 1231 RTD, 8 AI. Listed in the V20 documentation under the Advanced V20 license. Catalog firmware baseline is V2.1.1; the same V2.1 update path applies.
• 6ES7 231-5PF30-0XB0 – SM 1231 RTD with extended temperature range. Same firmware lineage, same fix.

If a third-party HMI is part of the same cell, the Pro-face TIA Portal Ethernet Driver V1.17.25 has been validated for secure TIA Portal V20 communication on the GP6000 series and WinGP runtime. Older driver builds (≤V1.15) will still connect but flag a security warning on first upload.

12. Troubleshooting Matrix